/**
  ******************************************************************************
  * @file    EEPROM_Emulation/src/eeprom.c 
  * @author  MCD Application Team
  * @version V1.7.0
  * @date    16-December-2016
  * @brief   This file provides all the EEPROM emulation firmware functions.
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */ 

/** @addtogroup EEPROM_Emulation
  * @{
  */ 

/* Includes ------------------------------------------------------------------*/
#include "eeprom.h"

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/

/* Global variable used to store variable value in read sequence */
uint16_t DataVar = 0;

/* Virtual address defined by the user: 0xFFFF value is prohibited */
uint16_t VirtAddVarTab[NB_OF_VAR];

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
static HAL_StatusTypeDef EE_Format(void);
static uint16_t EE_FindValidPage(uint8_t Operation);
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_VerifyPageFullyErased(uint32_t Address);

/*
********************************************************************************
** 函数名称 :	EE_LoadAllVar
** 描    述 :	从EEPROM中加载所有变量到指定的内存RAM中
** 输入参数 :	见函数说明
** 返    回 :	EE_OK：成功，其它：失败
********************************************************************************/
uint16_t EE_LoadAllVar(uint16_t *pRamVar)		/*[OUT]指向按照sEEPROM_VAR类型在内存RAM中申请的结构*/
{
	uint16_t res = 0;
	for (int i = 0; i < NB_OF_VAR; i++) {
		res = EE_ReadVariable(VirtAddVarTab[i], &pRamVar[i]);
		if (res != EE_OK) break;
	}
	return res;
}
/*
********************************************************************************
** 描述: 将给定内存RAM中的EEPROM变量首地址中的所有变量保存到EEPROM中. 若某个变量与已经保存的值相等则跳过.
** 返回: EE_OK：成功，其它：失败
********************************************************************************/
int EE_SaveAllVar(uint16_t *pRamVar)		/*[I]指向按照sEEPROM_VAR类型在内存RAM中申请的结构*/
{
	int res = 0;
	uint16_t data;
	for (int i = 0; i < NB_OF_VAR; i++) {
		res = EE_ReadVariable(VirtAddVarTab[i], &data);
		if (res > 1) break;	//res=0(EE_OK)找到变量, =1没发现变量保存过, =其它无效页
		if (res == 1 || data != pRamVar[i])
		{
			res = EE_WriteVariable(VirtAddVarTab[i], pRamVar[i]);
			if (res != EE_OK) break;
		}
	}
	return res;
}
/*
********************************************************************************
** 函数名称 :	EE_WriteVar
** 描    述 :	将指定变量写到EEPROM中指定的偏移位置
** 输入参数 :	见函数说明
** 返    回 :	EE_OK：成功，其它：失败
********************************************************************************/
uint16_t EE_WriteVar(uint16_t *pVar,			/*[IN]指向按照2字节对齐在内存RAM中申请的变量*/
										 uint16_t	offset,			/*[IN]变量在sEEPROM_VAR结构中的偏移双字节量*/
										 uint16_t num16)			/*[IN]变量所占双字节个数*/
{
	uint16_t res = 0;
	while (num16-- != 0) {
		res = EE_WriteVariable(VirtAddVarTab[offset], pVar[offset]);
		if (res != EE_OK) break;
		offset++;
	}
	return res;
}
/**
  * @brief  Restore the pages to a known good state in case of page's status
  *   corruption after a power loss.
  * @param  None.
  * @retval - Flash error code: on write Flash error
  *         - FLASH_COMPLETE: on success
  */
uint16_t EE_Init(void)
{
	uint16_t pagestatus0 = 0x1111, pagestatus1 = 6;
	uint16_t varidx = 0;
	uint16_t eepromstatus = 0, readstatus = 0;
	int16_t x = -1;
	HAL_StatusTypeDef  flashstatus;
	uint32_t page_error = 0;
	FLASH_EraseInitTypeDef s_eraseinit;

	for (varidx = 0; varidx < NB_OF_VAR; varidx++)
		VirtAddVarTab[varidx] = pagestatus0++;
	/* Unlock the Flash Program Erase controller */
	while (HAL_FLASH_Unlock() != HAL_OK);

	/* Get Page0 status */
	pagestatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);
	/* Get Page1 status */
	pagestatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

	/* Fill EraseInit structure*/
#ifdef FLASH_TYPEERASE_PAGES
	s_eraseinit.TypeErase   = FLASH_TYPEERASE_PAGES;
	s_eraseinit.PageAddress = PAGE0_BASE_ADDRESS;
	s_eraseinit.NbPages     = 1;
#else
	s_eraseinit.TypeErase		= FLASH_TYPEERASE_SECTORS;
	s_eraseinit.Sector			= START_SECTOR_NO;
	s_eraseinit.NbSectors		= 1;
	s_eraseinit.VoltageRange	= FLASH_VOLTAGE_RANGE_2;
#endif
  
	/* Check for invalid header states and repair if necessary */
	//保证: 页0是有效的页1是擦除的,或页0是擦除的页1是有效的
	switch (pagestatus0)
	{
	case ERASED:
		if (pagestatus1 == VALID_PAGE) /* Page0 erased, Page1 valid */
		{
			/* Erase Page0 */
			if (!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
			{
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
		}
		else if(pagestatus1 == RECEIVE_DATA) /* Page0 erased, Page1 receive */
		{
			/* Erase Page0 */
			if (!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
			{ 
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
			/* Mark Page1 as valid */
			flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, PAGE1_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
		}
		else /* First EEPROM access (Page0&1 are erased) or invalid state -> format EEPROM */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			flashstatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
		}
		break;

	case RECEIVE_DATA:
		if (pagestatus1 == VALID_PAGE) /* Page0 receive, Page1 valid */
		{
			/* Transfer data from Page1 to Page0 */
			for (varidx = 0; varidx < NB_OF_VAR; varidx++)
			{
				if ((*(__IO uint16_t*)(PAGE0_BASE_ADDRESS + 6)) == VirtAddVarTab[varidx])
				{
					x = varidx;
				}
				if (varidx != x)
				{
					/* Read the last variables' updates */
					readstatus = EE_ReadVariable(VirtAddVarTab[varidx], &DataVar);
					/* In case variable corresponding to the virtual address was found */
					if (readstatus != 0x1)
					{
						/* Transfer the variable to the Page0 */
						eepromstatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[varidx], DataVar);
						/* If program operation was failed, a Flash error code is returned */
						if (eepromstatus != HAL_OK)
						{
							return eepromstatus;
						}
					}
				}
			}
			/* Mark Page0 as valid */
			flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, PAGE0_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
#ifdef FLASH_TYPEERASE_PAGES
			s_eraseinit.PageAddress = PAGE1_BASE_ADDRESS;
#else
			s_eraseinit.Sector		= START_SECTOR_NO + 1;
#endif
			/* Erase Page1 */
			if (!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
			{ 
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
		}
		else if(pagestatus1 == ERASED) /* Page0 receive, Page1 erased */
		{
#ifdef FLASH_TYPEERASE_PAGES
			s_eraseinit.PageAddress = PAGE1_BASE_ADDRESS;
#else
			s_eraseinit.Sector		= START_SECTOR_NO + 1;
#endif
			/* Erase Page1 */
			if (!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
			{ 
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
			/* Mark Page0 as valid */
			flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, PAGE0_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
		}
		else /* Invalid state -> format eeprom */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			flashstatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
		}
		break;

	case VALID_PAGE:
		if (pagestatus1 == VALID_PAGE) /* Invalid state -> format eeprom */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			flashstatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
		}
		else if(pagestatus1 == ERASED) /* Page0 valid, Page1 erased */
		{
#ifdef FLASH_TYPEERASE_PAGES
			s_eraseinit.PageAddress = PAGE1_BASE_ADDRESS;
#else
			s_eraseinit.Sector		= START_SECTOR_NO + 1;
#endif
			/* Erase Page1 */
			if (!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
			{ 
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
		}
		else /* Page0 valid, Page1 receive */
		{
			/* Transfer data from Page0 to Page1 */
			for (varidx = 0; varidx < NB_OF_VAR; varidx++)
			{
				if ((*(__IO uint16_t*)(PAGE1_BASE_ADDRESS + 6)) == VirtAddVarTab[varidx])
				{
					x = varidx;
				}
				if (varidx != x)
				{
					/* Read the last variables' updates */
					readstatus = EE_ReadVariable(VirtAddVarTab[varidx], &DataVar);
					/* In case variable corresponding to the virtual address was found */
					if (readstatus != 0x1)
					{
						/* Transfer the variable to the Page1 */
						eepromstatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[varidx], DataVar);
						/* If program operation was failed, a Flash error code is returned */
						if (eepromstatus != HAL_OK)
						{
							return eepromstatus;
						}
					}
				}
			}
			/* Mark Page1 as valid */
			flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, PAGE1_BASE_ADDRESS, VALID_PAGE);        
			/* If program operation was failed, a Flash error code is returned */
			if (flashstatus != HAL_OK)
			{
				return flashstatus;
			}
#ifdef FLASH_TYPEERASE_PAGES
			s_eraseinit.PageAddress = PAGE0_BASE_ADDRESS;
#else
			s_eraseinit.Sector		= START_SECTOR_NO;
#endif
			/* Erase Page0 */
			if (!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
			{ 
				flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);
				/* If erase operation was failed, a Flash error code is returned */
				if (flashstatus != HAL_OK)
				{
					return flashstatus;
				}
			}
		}
		break;

	default:  /* Any other state -> format eeprom */
		/* Erase both Page0 and Page1 and set Page0 as valid page */
		flashstatus = EE_Format();
		/* If erase/program operation was failed, a Flash error code is returned */
		if (flashstatus != HAL_OK)
		{
			return flashstatus;
		}
		break;
	}

	return HAL_OK;
}

/**
  * @brief  Verify if specified page is fully erased.
  * @param  Address: page address
  *   This parameter can be one of the following values:
  *     @arg PAGE0_BASE_ADDRESS: Page0 base address
  *     @arg PAGE1_BASE_ADDRESS: Page1 base address
  * @retval page fully erased status:
  *           - 0: if Page not erased
  *           - 1: if Page erased
  */
uint16_t EE_VerifyPageFullyErased(uint32_t Address)
{
  uint32_t readstatus = 1;
  uint16_t addressvalue = 0x5555;
    
  /* Check each active page address starting from end */
  while (Address <= PAGE0_END_ADDRESS)
  {
    /* Get the current location content to be compared with virtual address */
    addressvalue = (*(__IO uint16_t*)Address);

    /* Compare the read address with the virtual address */
    if (addressvalue != ERASED)
    {
      
      /* In case variable value is read, reset readstatus flag */
      readstatus = 0;

      break;
    }
    /* Next address location */
    Address = Address + 4;
  }
  
  /* Return readstatus value: (0: Page not erased, 1: Page erased) */
  return readstatus;
}

/**
  * @brief  Returns the last stored variable data, if found, which correspond to
  *   the passed virtual address
  * @param  VirtAddress: Variable virtual address
  * @param  Data: Global variable contains the read variable value
  * @retval Success or error status:
  *           - 0: if variable was found
  *           - 1: if the variable was not found
  *           - NO_VALID_PAGE: if no valid page was found.
  */
uint16_t EE_ReadVariable(uint16_t VirtAddress, uint16_t* Data)
{
	uint16_t validpage = PAGE0;
	uint16_t addressvalue = 0x5555, readstatus = 1;
	uint32_t address = EEPROM_START_ADDRESS, PageStartAddress = EEPROM_START_ADDRESS;

	/* Get active Page for read operation */
	validpage = EE_FindValidPage(READ_FROM_VALID_PAGE);

	/* Check if there is no valid page */
	if (validpage == NO_VALID_PAGE)
	{
		return NO_VALID_PAGE;
	}

	/* Get the valid Page start Address */
	PageStartAddress = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(validpage * PAGE_SIZE));

	/* Get the valid Page end Address */
	address = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + validpage) * PAGE_SIZE));

	/* Check each active page address starting from end */
	while (address > (PageStartAddress + 2))
	{
		/* Get the current location content to be compared with virtual address */
		addressvalue = (*(__IO uint16_t*)address);

		/* Compare the read address with the virtual address */
		if (addressvalue == VirtAddress)
		{
			/* Get content of Address-2 which is variable value */
			*Data = (*(__IO uint16_t*)(address - 2));

			/* In case variable value is read, reset readstatus flag */
			readstatus = 0;

			break;
		}
		else
		{
			/* Next address location */
			address = address - 4;
		}
	}

	/* Return readstatus value: (0: variable exist, 1: variable doesn't exist) */
	return readstatus;
}

/**
  * @brief  Writes/upadtes variable data in EEPROM.
  * @param  VirtAddress: Variable virtual address
  * @param  Data: 16 bit data to be written
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
uint16_t EE_WriteVariable(uint16_t VirtAddress, uint16_t Data)
{
  uint16_t Status = 0;

  /* Write the variable virtual address and value in the EEPROM */
  Status = EE_VerifyPageFullWriteVariable(VirtAddress, Data);

  /* In case the EEPROM active page is full */
  if (Status == PAGE_FULL)
  {
    /* Perform Page transfer */
    Status = EE_PageTransfer(VirtAddress, Data);
  }

  /* Return last operation status */
  return Status;
}

/**
  * @brief  Erases PAGE and PAGE1 and writes VALID_PAGE header to PAGE
  * @param  None
  * @retval Status of the last operation (Flash write or erase) done during
  *         EEPROM formating
  */
static HAL_StatusTypeDef EE_Format(void)
{
  HAL_StatusTypeDef flashstatus = HAL_OK;
  uint32_t page_error = 0;
  FLASH_EraseInitTypeDef s_eraseinit;

#ifdef FLASH_TYPEERASE_PAGES
	s_eraseinit.TypeErase   = FLASH_TYPEERASE_PAGES;
	s_eraseinit.PageAddress = PAGE0_BASE_ADDRESS;
	s_eraseinit.NbPages     = 1;
#else
	s_eraseinit.TypeErase		= FLASH_TYPEERASE_SECTORS;
	s_eraseinit.Sector			= START_SECTOR_NO;
	s_eraseinit.NbSectors		= 1;
	s_eraseinit.VoltageRange	= FLASH_VOLTAGE_RANGE_2;
#endif
  /* Erase Page0 */
  if(!EE_VerifyPageFullyErased(PAGE0_BASE_ADDRESS))
  {
    flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error); 
    /* If erase operation was failed, a Flash error code is returned */
    if (flashstatus != HAL_OK)
    {
      return flashstatus;
    }
  }
  /* Set Page0 as valid page: Write VALID_PAGE at Page0 base address */
  flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, PAGE0_BASE_ADDRESS, VALID_PAGE); 
  /* If program operation was failed, a Flash error code is returned */
  if (flashstatus != HAL_OK)
  {
    return flashstatus;
  }

#ifdef FLASH_TYPEERASE_PAGES
	s_eraseinit.PageAddress = PAGE1_BASE_ADDRESS;
#else
	s_eraseinit.Sector			= START_SECTOR_NO + 1;
#endif
  /* Erase Page1 */
  if(!EE_VerifyPageFullyErased(PAGE1_BASE_ADDRESS))
  {  
    flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error); 
    /* If erase operation was failed, a Flash error code is returned */
    if (flashstatus != HAL_OK)
    {
      return flashstatus;
    }
  }
  
  return HAL_OK;
}

/**
  * @brief  Find valid Page for write or read operation
  * @param  Operation: operation to achieve on the valid page.
  *   This parameter can be one of the following values:
  *     @arg READ_FROM_VALID_PAGE: read operation from valid page
  *     @arg WRITE_IN_VALID_PAGE: write operation from valid page
  * @retval Valid page number (PAGE or PAGE1) or NO_VALID_PAGE in case
  *   of no valid page was found
  */
static uint16_t EE_FindValidPage(uint8_t Operation)
{
  uint16_t pagestatus0 = 6, pagestatus1 = 6;

  /* Get Page0 actual status */
  pagestatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);

  /* Get Page1 actual status */
  pagestatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

  /* Write or read operation */
  switch (Operation)
  {
    case WRITE_IN_VALID_PAGE:   /* ---- Write operation ---- */
      if (pagestatus1 == VALID_PAGE)
      {
        /* Page0 receiving data */
        if (pagestatus0 == RECEIVE_DATA)
        {
          return PAGE0;         /* Page0 valid */
        }
        else
        {
          return PAGE1;         /* Page1 valid */
        }
      }
      else if (pagestatus0 == VALID_PAGE)
      {
        /* Page1 receiving data */
        if (pagestatus1 == RECEIVE_DATA)
        {
          return PAGE1;         /* Page1 valid */
        }
        else
        {
          return PAGE0;         /* Page0 valid */
        }
      }
      else
      {
        return NO_VALID_PAGE;   /* No valid Page */
      }

    case READ_FROM_VALID_PAGE:  /* ---- Read operation ---- */
      if (pagestatus0 == VALID_PAGE)
      {
        return PAGE0;           /* Page0 valid */
      }
      else if (pagestatus1 == VALID_PAGE)
      {
        return PAGE1;           /* Page1 valid */
      }
      else
      {
        return NO_VALID_PAGE ;  /* No valid Page */
      }

    default:
      return PAGE0;             /* Page0 valid */
  }
}

/**
  * @brief  Verify if active page is full and Writes variable in EEPROM.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data)
{
  HAL_StatusTypeDef flashstatus = HAL_OK;
  uint16_t validpage = PAGE0;
  uint32_t address = EEPROM_START_ADDRESS, pageendaddress = EEPROM_START_ADDRESS+PAGE_SIZE;

  /* Get valid Page for write operation */
  validpage = EE_FindValidPage(WRITE_IN_VALID_PAGE);
  
  /* Check if there is no valid page */
  if (validpage == NO_VALID_PAGE)
  {
    return  NO_VALID_PAGE;
  }

  /* Get the valid Page start address */
  address = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(validpage * PAGE_SIZE));

  /* Get the valid Page end address */
  pageendaddress = (uint32_t)((EEPROM_START_ADDRESS - 1) + (uint32_t)((validpage + 1) * PAGE_SIZE));

  /* Check each active page address starting from begining */
  while (address < pageendaddress)
  {
    /* Verify if address and address+2 contents are 0xFFFFFFFF */
    if ((*(__IO uint32_t*)address) == 0xFFFFFFFF)
    {
      /* Set variable data */
      flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, address, Data);       
      /* If program operation was failed, a Flash error code is returned */
      if (flashstatus != HAL_OK)
      {
        return flashstatus;
      }
      /* Set variable virtual address */
      flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, address + 2, VirtAddress);       
      /* Return program operation status */
      return flashstatus;
    }
    else
    {
      /* Next address location */
      address = address + 4;
    }
  }

  /* Return PAGE_FULL in case the valid page is full */
  return PAGE_FULL;
}

/**
  * @brief  Transfers last updated variables data from the full Page to
  *   an empty one.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data)
{
	HAL_StatusTypeDef flashstatus = HAL_OK;
	uint32_t newpageaddress = EEPROM_START_ADDRESS;
	uint32_t oldpageid = 0;
	uint16_t validpage = PAGE0, varidx = 0;
	uint16_t eepromstatus = 0, readstatus = 0;
	uint32_t page_error = 0;
	FLASH_EraseInitTypeDef s_eraseinit;

	/* Get active Page for read operation */
	validpage = EE_FindValidPage(READ_FROM_VALID_PAGE);

	if (validpage == PAGE1)       /* Page1 valid */
	{
		/* New page address where variable will be moved to */
		newpageaddress = PAGE0_BASE_ADDRESS;

		/* Old page ID where variable will be taken from */
#ifdef FLASH_TYPEERASE_PAGES
		oldpageid = PAGE1_BASE_ADDRESS;
#else
		oldpageid = START_SECTOR_NO + 1;
#endif
	}
	else if(validpage == PAGE0)  /* Page0 valid */
	{
		/* New page address  where variable will be moved to */
		newpageaddress = PAGE1_BASE_ADDRESS;

		/* Old page ID where variable will be taken from */
#ifdef FLASH_TYPEERASE_PAGES
		oldpageid = PAGE0_BASE_ADDRESS;
#else
		oldpageid = START_SECTOR_NO;
#endif
	}
	else
	{
		return NO_VALID_PAGE;       /* No valid Page */
	}

	/* Set the new Page status to RECEIVE_DATA status */
	flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, newpageaddress, RECEIVE_DATA);  
	/* If program operation was failed, a Flash error code is returned */
	if (flashstatus != HAL_OK)
	{
		return flashstatus;
	}
  
	/* Write the variable passed as parameter in the new active page */
	eepromstatus = EE_VerifyPageFullWriteVariable(VirtAddress, Data);
	/* If program operation was failed, a Flash error code is returned */
	if (eepromstatus != HAL_OK)
	{
		return eepromstatus;
	}

	/* Transfer process: transfer variables from old to the new active page */
	for (varidx = 0; varidx < NB_OF_VAR; varidx++)
	{
		if (VirtAddVarTab[varidx] != VirtAddress)  /* Check each variable except the one passed as parameter */
		{
			/* Read the other last variable updates */
			readstatus = EE_ReadVariable(VirtAddVarTab[varidx], &DataVar);
			/* In case variable corresponding to the virtual address was found */
			if (readstatus != 0x1)
			{
				/* Transfer the variable to the new active page */
				eepromstatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[varidx], DataVar);
				/* If program operation was failed, a Flash error code is returned */
				if (eepromstatus != HAL_OK)
				{
					return eepromstatus;
				}
			}
		}
	}

	#ifdef FLASH_TYPEERASE_PAGES
	s_eraseinit.TypeErase   = FLASH_TYPEERASE_PAGES;
	s_eraseinit.PageAddress = oldpageid;
	s_eraseinit.NbPages     = 1;
#else
	s_eraseinit.TypeErase		= FLASH_TYPEERASE_SECTORS;
	s_eraseinit.Sector			= oldpageid;
	s_eraseinit.NbSectors		= 1;
	s_eraseinit.VoltageRange	= FLASH_VOLTAGE_RANGE_2;
#endif
  
	/* Erase the old Page: Set old Page status to ERASED status */
	flashstatus = HAL_FLASHEx_Erase(&s_eraseinit, &page_error);  
	/* If erase operation was failed, a Flash error code is returned */
	if (flashstatus != HAL_OK)
	{
		return flashstatus;
	}

	/* Set new Page status to VALID_PAGE status */
	flashstatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_HALFWORD, newpageaddress, VALID_PAGE);   
	/* If program operation was failed, a Flash error code is returned */
	if (flashstatus != HAL_OK)
	{
		return flashstatus;
	}
  
  

	/* Return last operation flash status */
	return flashstatus;
}

/**
  * @}
  */ 

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
